A rebar plugin
$ rebar3 compile
Add the plugin to your rebar config:
{plugins, [
{rebar3_cargo, {git, "https://host/user/rebar3_cargo.git", {tag, "0.1.0"}}}
]}.
Then just call your plugin directly in an existing application:
$ rebar3 rebar3_cargo
===> Fetching rebar3_cargo
===> Compiling rebar3_cargo
<Plugin Output>